The advent of satellite-based, or Global Positioning System (GPS), navigation had a huge impact on US aviation after the Federal Aviation Administration (FAA) first introduced it in Instrument Flight Rules operations in 1994. GPS is now the primary means of navigation for most aircraft, though many still rely on traditional ground-based aids such as DME, VOR, TACAN (DVT), and ILS.

Some believe that aviation has become overly reliant on GPS. Satellite navigation is vulnerable to disruption and outages. Even small and inexpensive spoofing and jamming devices used by truck drivers to conceal their location from employers have been known to cause major issues for pilots.

More destructive attacks are also becoming commonplace. In the past five years, more than 10,000 incidents of GPS interference have been linked to China and Russia. GPS is an easy target and interference can cause big issues globally, where like in the US, aviation and economies are so closely tied.  Fortunately, the US has a strong back-up navigation system in its ground-based NAVAIDS, thousands of which are in place across the states.

“With the increased amount of GPS jamming interference throughout the world, the ground-based systems are now in the forefront of safely navigating planes to and from airports,” says Terry Thomas, vice president of programs at Selex, a leading American manufacturer of communication, navigation, and surveillance equipment.

“The United States airspace is quite unique as compared to the rest of the world,” adds Kenneth Cleveland, Selex’s vice president of sales and marketing. “We have the largest and most crowded general aviation airspace. Many aircraft rely on ground-based systems, not just for a backup but also as a primary use of navigation. Overall, the ground-based infrastructure is critical based upon the geography of the United States and the number of remote locations that have airports.”

For this reason, it’s vital that these systems are kept in full working order. Afterall, most of America’s ground-based NAVAIDS were put in place in the 1980s, making them around 40 years old today. And while this stands testament to the FAA’s ability to maintain this infrastructure and keep the airspace operating safely even with aging equipment, it is beginning to raise concerns for how much longer these NAVAIDS can or should be relied upon.

“The design life of these NAVAIDS is around 20 years, but they often last 30 and sometimes 40 years. On average, our international customers replace theirs every 15 to 20 years,” says Jennifer Campbell, Selex’s director of government programs for air traffic management.

She adds that while the FAA is planning to implement a program to maintain and modernize this equipment, the industry would like to see a more rapid acceleration of the program.

“One analogy we use sometimes is that you wouldn’t want a 25-year-old smoke detector in your living room. You would want to try to replace it with a more modern version so that you’d have the safest product available on the market. That’s why we feel so passionately about the need for a modern and resilient ground-based navigation infrastructure,” she adds.

Obsolescence and environmental concerns

There are other risks associated with aging NAVAIDS, including obsolescence. A transistor made 40 years ago simply isn’t available anymore. If there’s no obtainable spare part, it means a redesign of the system. This is often a lengthy process due to the FAA’s requirement to validate the system for safety and reliability before its use.

This can have cost implications down the line. The combination of bad weather conditions and an out-of-service NAVAID at an airport means an aircraft is unable to land there, which will have an economic impact to that community.

The carbon footprint of legacy equipment is another important concern. “The carbon footprint for a newer navigational aid system is much smaller; it uses less energy and is more efficient. If you’re looking at hundreds or thousands of airports, that’s quite a lot of energy savings,” explains Thomas.

Recent calculations show that a modern VORTAC is nearly seven times more energy efficient than its legacy counterpart. In fact, if every VORTAC in the NAS operating outside its service life was replaced, it could save the equivalent energy usage of a small town. Moreover, modern distance measuring equipment (DME) used in a DME-to-DME network can also lead to more fuel-efficient flight routes than previous methods.

In the continued development and improvement of its air traffic management systems including NAVAIDS, Selex has become an industry leader by reducing the energy consumption of the most power-hungry components of its DVT equipment.

The company is also working on developing systems with fewer components, thereby making its NAVAIDS easier to manufacture and maintain while further reducing carbon footprints. As reflected in the FAA’s recent net-zero emissions by 2050 climate action plan, curbing climate change is a key focus for the aviation industry, and Selex is proud that its equipment can be a part of that.

Above all, the company’s key mission is to deliver the essential technology needed for seamless, safe travel for American and global passengers. Selex produces all its equipment from its facility in Overland Park, Kansas, right in the heartland of America, and sources almost entirely from suppliers around the US.

“We like to say that we connect the world without the world knowing we’re there,” adds Cleveland. “We take a lot of pride in this because we really do believe that we help to increase and improve safety for travelers around the world.”